<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
var arr1=new Array(12,55,34,78,676);
var arr2=new Array(12,33,1);

Array.prototype.sum=function()  //class,
//arr.sum=function()           //类似于行间样式
{
	var result=0;
	
	for(var i=0;i<this.length;i++)
	{
		result+=this[i];
	}
	return result;
};
alert(arr1.sum());
alert(arr2.sum());
</script>
</head>

<body>
</body>
</html>
